Gasoline composition containing lead compounds



United States Patent Ofi lice 3,195,992 Patented July 20, 1965 3,195,992 GASQLIYE COMPfiSlTlfiN QGNTAINLIG LEAD COMPQUNDS Donal R. Gison, San Pablo, Maurice ll. Baruscii, Richmend, Wallace 1. Richardson, Lafayette, and George J. Kautslry, El Qerrito, Caiii, assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Mint. 2?, 1959, Ser. No. 802,322

1 Claim. (G. 44-69) This invention relates to an improved gasoline composition containing .lead compounds. More particularly, the invention is concerned with a superior new hydrocarbon fuel of the gasoline boiling range containing a mixture of tetramethyl lead and ethyltrimethyl lead.

Gasoline compositions of high octane number are commonly required for modern spark ignition internal combustion automobile and aircraft engines. Engines of these types in general use today are designed with high compression ratios for more efiicient operation. Since the present trend is toward engines of still higher compression ratios for increased power and improved performance, there is a constant demand for gasoline compositions of even higher octane number.

Improved methods of refining and blending gasoline base stocks, and additives such as lead tetraethyl, have been employed to meet the demands for higher octane number gasoline compositions. However, it has been generally realized that there is at present a limit to the improvement in octane number that can be obtained by such conventional methods and additives. New gasoline base stocks with the combination of different additives are greatly needed, therefore, to avoid present limitations and provide gasoline compositions of high octane number for future use in automotive and aircraft engines.

In our copending application Serial No. 765,920, filed September 26, 1958, improved gasoline compositions containing certain amounts of tetramethyl lead in particular hydrocarbon base fuels are disclosed. In that application, such compositions are shown to be unexpectedly superior to similar gasoline compositions containing the commonly accepted tetraethyl lead additive.

Also, in another copending application Serial No. 802,521, filed March 27, 1959 now abandoned, we have disclosed a superior new gasoline composition of a particular type containing ethyltrimethyl lead. Such compositions are shown to have high octane numbers which are surprisingly equivalent to the above-mentioned outstanding tetrarnethyi lead gasoline composition.

In accordance with the present invention, it has been further found that a gasoline composition having an octane number unexpectedly higher than either of the above-mentioned types of improved gasoline composition is obtained in a leaded gasoline composition comprising a hydrocarbon base fuel of the gasoline boiling range, (a) about 25% by volume of said base fuel boiling in the range of about 90 to about 150 F. and having from about 30 to about 80% by volume of parafiins and naphthenes, from about to about 60% by volume olefms, not more than about 10% by volume aromatics and an octane number of at least 85, (b) about by volume of said base fuel boiling in the range of about 150 to about 200 F. and having from about 20 to about 70% by volume of paraffins and naphthenes, from about 20 to about 60% by volume of olefins and from about 10 to about by volume of aromatics, (c) about by volume of said base fuel boiling in the range of about 200 to about 425 F. and having from about 20 to about 80% by volume of pareflins and naphthenes, from about 20 to about 80% by volume of aromatics and not more than about 20% by volume of olefins, said base fuel having an octane number of about to about 100, there being incorporated in said base fuel a mixture consisting of about 10 to about by weight of tetramethyl lead and from about 10 to about 90% of ethy-ltrimethyl lead, said mixture being present in the gasoline composition in an amount sufiicient to improve the octane number.

The new improved gasoline composition of the present invention containing the mixture of tetramethyl lead and ethyltrimethyl lead has an unexpectedly higher octane number compared to previously known gasoline compositions of the same type containing either tetramethyl or ethyltrimethyl lead alone. This is surprising since it would be expected that the octane number of the mixture of tetramethyl lead and ethyltrimethyl lead in the gasoline would be cumulative and nearly equal to the arithmetical average of the octane number of fuels containing tetramethyl lead and ethyltrimethyl lead individually. In particular, in gasoline compositions containing conventional amounts of lead, for example, from 1.5 to 4 grams of lead per gallon, the octane number improvement by the mixture of tetrametbyl lead and ethyltrimethyl lead is even more pronounced and actually exceeds the octane number of the same gasoline with either tetramethyl lead or ethyltrimethyl lead alone.

The hydrocarbon base fuel of the composition according to the invention is conveniently prepared by the usual refining and blending processes. It normally contains straigh -chain parafiins, branched-chain paraifins, olefins, aromatics and naphthenes.

As already mentioned, the base fuel is a hydrocarbon fuel boiling in the gasoline boiling range. Generally described, such fuels have an ASTM (D-S6) distillation with an initial boiling point of about 90 F. and a final boiling point of about 425 F. The unleaded base fuel has a research octane number of about 85 to about as determined by the accepted CPR engine test method.

For our purposes, the base fuel is most conveniently described as being characterized by three distinguishable portions of a certain boiling range and hydrocarbon construction. A low boiling portion is present amounting to about 25% by volume of said base fuel and boiling in the range of about 90 to about F. This por tion contains from about 30 to about 80%. preferably about 50 to about 65%, by volume of paraflins and naphthenes, from about 20 to about 60%, preferably from about 20 to about 40%, by volume of olefins and not more than about 10% by volume of aromatics. It has an octane number of at least 85 and preferably at least 90. Also present is an intermediate boiling portion amounting to about 25% by volume of said base fuel and boiling in the range of about 150 to about 200 F. This portion has from about 20 to about 70% by volume of paraflins and naphthenes, from about 20 to about 60% by volume of olefins and from about 10 to about 30% by volume of aromatics. The higher boiling por tion of the hydrocarbon base fuel amounts to about 50% by volume and boils in the range of about 200 to about 425 F. This portion contains from about 20 to about 80% by volume of paratlins and naphthenes, from about 20 to 80% by volume of aromatics and not more than about 20% by volume of olefins.

in the foregoing description, the temperature ranges for the different portions may vary by minor amounts of 10 F. or less as will be understood by those skilled in the art.

The mixture of tetramethyl lead and ethyltrirnethyl lead in the leaded gasoline composition according to the invention may be produced by various means. For example, the lead compounds may be added to the gasoline individually in amounts to give the required blend of 10 to 90% by weight. The individual lead compounds may be u also mixed in suitable proportions and the mixture then added to the base gasoline. The tetramethyl lead and ethyltrimethyl lead mixture is employed in the gasoline composition of the invention preferably in amounts of 0.5 gram per gallon of base fuel. In these amounts, the combined effect of the two different compounds in the base fuel provides an octane number improvement which is significantly greater than that which would be expected from an arithmetic average of octane numbers obtained with the individual lead compounds in the same base gasoline. The outstanding effect of the mixed tetrarnethyl lead and ethyltrimethyl lead compounds is most pronounced in gasoline compositions containing from 1.5 to 4 grams of lead per gallon of base fuel. As mentioned above, the octane number improvement with the mixture in these amounts is greater than the octane number improvement of either of the lead compounds alone.

Other gasoline additives, such as scavengers like ethylene chloride or bromide, oxidation inhibitors, corrosion inhibitors, surface ignition suppressants like phosphorus compounds, detergents, and the like may be present.

The superior new gasoline composition containing lead compounds in accordance with the present invention'is further illustrated by the compositions and tests thereon given in the following examples. These tests show the improved octane number of the combination of tetramethyl lead and ethyltrimethyl lead in the hydrocarbon base fuel as compared to compositions containing either of the lead compounds alone.

In the examples, the base fuels are typical hydrocarbon fuels boiling in the gasoline range. Fuel A has the following ASTM (D-86) distillation with the other base fuels being essentially the same.

TABLE 1 Boiling Percent Percent Base Cut Octane Range, Parafiins Percent Aromat- Fuel No. Number F. and Olefins ics Naphthenes *Calculated from blending values.

Tables II and III which follow are summaries of the pertinent data of the examples. The tables show the comparative effect on octane number by the addition of ethyltrimethyl lead (ETML), tetramethyl lead (TML) and representative mixtures of ethyltrimethyl lead and tetramethyl lead. Table II shows the octane number effect of the different base fuels leaded to 3.18 grams of lead per gallon of base fuel. Table 111 shows the effect of fuels leaded to 1.06 grams of lead per gallon of base fuel.

The octane number in this comparison is based on the road octane rating method. These ratings are determined by chassis dynamometer tests in accordance with the Modified Uniontown Test Procedure. In the determinations, three different makes of automobiles of recent manufac- Percent distilled: F. Initial boiling point 9O ture (1956-1958) are employed, some of which are IIlOdl- 10 115 fied to provide increased compression ratios. At standard 5 0 203 timing, the octane requirement of these automobiles ranges 9O 342 from about 94 to 102 octane numbers. The Compression End point 410 ratios vary from about 8.5:1 to as high as about 12:1.

TABLE II Number of Base Car ETML TML 25% TML v D1 TML D1 75% TML D1 Determi- Fuel 75% ETML 50% ETML 25% ETML nations A Car No. 95. 70 90.10 90.03 0.82 90.30 0. 41 95.89 -0. 07

Car No. 100.30 100. 03 100.00 0. 33 100. 62 0. 51 100.43 0. 35 0 Car No. 98.72 93. 92 99. 24 0.43 99. 24 0. 42 99. 44 0. 54

B CarNo. 95.93 l 90.17 Car No. 100.13 100.30

0 GarNo.1 97.20 97.17 Car No. 100.77 100.93

D Car No. 1 96. 90 97. 33 Car No. 3 100. 43 100. 53

D is difierence between actual value and Average Improvement (D).

Table I which follows shows the essential hydrocarbon composition and characteristics of the illustrative base hydrocarbon fuels employed in the examples. The clear octane number of the fuels is the accepted Research octane number usually given in designating a certain gasoline. Such octane numbers are obtained by Research Method D-905. in ASTM Manual of Engine Test Methods for Rating Fuels. The distillation fractions are taken from a typical ASTM (D-86) type distillation. Cut 1 is the first 25 percent volume distilled; cut 2 is the 25 to 50 percent volume fraction and cut 3 is the final 50 percent volu-me distilled.

linear interpolation between ETML and TML values in mixture.

t D is difference between actual value and linear interpolation beveen ETML and TML values.

The examples in the above tables show that the improved gasoline compositions containing mixed lead compounds in accordance with the invention give significantly improved octane number ratings compared to similar gasoline compositions containing either of the lead compounds alone. The octane number improvements with conventional amounts of lead above 1.5 grams per gallon for the mixed tetramethyl and ethyltrimethyl, particularly with about 50% by Weight or more of the ethyltrimethyl lead in the mixture are exceptionally outstanding.

We claim:

A leaded gasoline composition consisting essentially of a major proportion of a hydrocarbon base fuel of the gasoline boiling range, (a) about 25% by volume of said base fuel boiling in the range of about 90 to about 150 F. and having from about 50 to about 65% by volume of paraflins and naphthenes, from about 20 to about 40% by volume of olefins, not more than about by volume of aromatics and a clear Research octane number of at least 90, (b) about 25% by volume of said base fuel boiling in the range of about 150 to about 200 F. and having from about 20 to about 70% by volume of paraffius and naphthenes, from about 20 to about 60% by volume of olefins and from about 10 to about 30% by volume of aromatics, (c) about 50% by volume of said base fuel boiling in the range of about 200 to about 425 F. and having from about 20 to about 80% by volume of paraifins and naphthenes, from about 20 to about 80% by volume of aromatics and not more than about 20% by volume of olefins, said base fuel having a clear Research octane number of about 85 to about 100, there being incorporated in said base fuel a mixture consisting of from about 25 to about by Weight of tetramethyl lead and ethyltrirnethyl lead, from about 50 to about by Weight of said mixture being present in the gasoline composition in an amount equivalent to about 1.5 to 4 grams of lead per gallon of base fuel.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Paper presented before 22nd meeting of the American Petroleum Institute, Nov. 7, 1941, Improved Motor Fuels Through Selective Blending, by Wagner et al., 19 pages.

Industrial & Engineering Chemistry, December 1948, vol. 40, N0. 12, Knocking Characteristics of Hydrocarbons, by Lovell, pages 2388-2397 (complete article pages 23882438).

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, ALPHONSO D. SULLIVAN,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patnet No. 3,195,992 July 20, 1965 Donel R. Olson et a1.

It is hereby certified that error appears in the above numbered petent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 2, after "and" insert from about 50 to about 75% by weight of lines 3 and 4, strike out "from abo' 50 to about 75% by weight of".

Signed and sealed this 25th day of January 1966.

Atteet:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

